The regulation of eukaryotic genes involves many hundreds of proteins. How they work together at the many thousands of genes that comprise a genome is not known. Little is known about how this interplay changes as cellular genomes are reprogrammed in response to signaling events such as environmental stress. The work proposed here is a continuation of a project to broadly survey where transcriptional regulatory proteins are located throughout the genome of the model eukaryotic organism Saccharomcyes cerevisiae, and where they translocate to when the genome is reprogrammed by environmental signals, such as heat shock and other stresses. Heat shock provides a rapid and simple programming event for the cell. Current studies on this project have already revealed novel insights into gene regulation by demonstrating that pre-initiation complexes partially assemble in nucleosome-free promoter regions. However, full assembly requires removal of the -1 nucleosome located on the upstream side of the promoter. The genomic location of ~200 gene- and chromatin-regulatory proteins have been determined at low resolution by ChIP-chip, under normal and heat shock conditions. The data is now being analyzed. High resolution mapping will be achieved by retrofitting the ChIP-chip libraries for ChIP-seq. Even higher resolution mapping will be achieved on a select set of factors using reagents to trim the ChIP DNA. Relationships among binding events will provide new insights into transcription complex assembly and regulation.